Mercury

More detailed data from MESSENGER shows that volcanoes exploded on Mercury for a substantial portion of the planet’s history. The findings suggest Mercury not only had volatiles but held on to them for longer than scientists had expected.

New data show that the innermost planet has contracted far more than previously thought. The findings are key to understanding the planet’s history and the structure of its unusually large metallic core.

Data from NASA's MESSENGER spacecraft supports the hypothesis that the planet Mercury harbors abundant water ice in its permanently shadowed craters. The finding is helping astrobiologists understand how water may have been delivered to planets like Earth as the Solar System formed.

Tiny pieces of rock captured from the astroid Itokawa by the Japanese mission Hayabusa are now being analyzed. It is the first time asteroid samples have been returned to Earth, and they could help astrobiologists understand the origin of the Solar System.

Astrobiology Magazine is highlighting the top 10 stories of 2011. At number eight, NASA's MESSENGER spacecraft returns a wealth of surprising data from the tiny planet Mercury. (Originally published 10/12/2011)